Bacteria Causing Upper Respiratory Tract Infections PDF

Bacteria Causing Upper Respiratory Tract Infections Dr. Shokri Mohsen Lecturer of Microbiology and Immunology Case Study: A 25-year-old patient presents to the clinic with complaints of a sore throat, fever, and difficulty swallowing. The patient reports a sudden onset of symptoms over...

Bacteria Causing Upper Respiratory Tract Infections Dr. Shokri Mohsen Lecturer of Microbiology and Immunology Case Study: A 25-year-old patient presents to the clinic with complaints of a sore throat, fever, and difficulty swallowing. The patient reports a sudden onset of symptoms over the last 24 hours, accompanied by a fever of 38.3°C. There is no significant medical history of chronic illnesses or recent travel. Upon examination, the patient appears unwell and has erythema and swelling of the tonsils. The throat is red and exhibits white patches. The patient has tender cervical lymphadenopathy. There is no cough, rhinorrhea, or other respiratory symptoms. The clinical presentation raises suspicions of a bacterial upper respiratory tract infection, possibly streptococcal pharyngitis. The differential diagnosis includes viral pharyngitis (e.g., caused by adenovirus or Epstein-Barr virus) and bacterial pharyngitis, with Streptococcus pyogenes (Group A Streptococcus) being a primary concern. Case Study: A 25-year-old patient presents to the clinic with complaints of a sore throat, fever, and difficulty swallowing. The patient reports a sudden onset of symptoms over the last 24 hours, accompanied by a fever of 38.3°C. There is no significant medical history of chronic illnesses or recent travel. Upon examination, the patient appears unwell and has erythema and swelling of the tonsils. The throat is red and exhibits white patches. The patient has tender cervical lymphadenopathy. There is no cough, rhinorrhea, or other respiratory symptoms. The clinical presentation raises suspicions of a bacterial upper respiratory tract infection, possibly streptococcal pharyngitis. The differential diagnosis includes viral pharyngitis (e.g., caused by adenovirus or Epstein-Barr virus) and bacterial pharyngitis, with Streptococcus pyogenes (Group A Streptococcus) being a primary concern. Case Study: A 25-year-old patient presents to the clinic with complaints of a sore throat, fever, and difficulty swallowing. The patient reports a sudden onset of symptoms over the last 24 hours, accompanied by a fever of 38.3°C. There is no significant medical history of chronic illnesses or recent travel. Upon examination, the patient appears unwell and has erythema and swelling of the tonsils. The throat is red and exhibits white patches. The patient has tender cervical lymphadenopathy. There is no cough, rhinorrhea, or other respiratory symptoms. The clinical presentation raises suspicions of a bacterial upper respiratory tract infection, possibly streptococcal pharyngitis. The differential diagnosis includes viral pharyngitis (e.g., caused by adenovirus or Epstein-Barr virus) and bacterial pharyngitis, with Streptococcus pyogenes (Group A Streptococcus) being a primary concern. Case Study: A 25-year-old patient presents to the clinic with complaints of a sore throat, fever, and difficulty swallowing. The patient reports a sudden onset of symptoms over the last 24 hours, accompanied by a fever of 38.3°C. There is no significant medical history of chronic illnesses or recent travel. Upon examination, the patient appears unwell and has erythema and swelling of the tonsils. The throat is red and exhibits white patches. The patient has tender cervical lymphadenopathy. There is no cough, rhinorrhea, or other respiratory symptoms. The clinical presentation raises suspicions of a bacterial upper respiratory tract infection, possibly streptococcal pharyngitis. The differential diagnosis includes viral pharyngitis (e.g., caused by adenovirus or Epstein-Barr virus) and bacterial pharyngitis, with Streptococcus pyogenes (Group A Streptococcus) being a primary concern.  Appropriate Diagnostic Tests: 1. Rapid Streptococcal Antigen 2. Throat Culture: Test (RADT): Purpose: To quickly determine Purpose: To confirm the the presence of group A presence of Streptococcus streptococcal antigens. pyogenes and identify antibiotic RADT provides rapid results susceptibility. within minutes but may have Throat cultures are more slightly lower sensitivity sensitive than RADT but take compared to throat cultures. longer (24-48 hours) to provide results.  Decision-Making for Antibiotic Therapy: 1. Positive RADT Result: 2. Negative RADT Result: If the rapid streptococcal antigen A negative result does not rule out test is positive, it indicates the bacterial infection, as RADT presence of group A streptococci, sensitivity is not 100%. supporting the diagnosis of bacterial In such cases, consider a throat pharyngitis. culture to confirm the diagnosis. Initiate antibiotic therapy promptly, If the patient is severely ill or at high typically with penicillin or amoxicillin risk of complications, the healthcare as the first-line treatment. provider might decide to start empirical antibiotic therapy while awaiting culture results.  Choice of Antibiotics: 2. Cephalosporins or 1. Penicillin or Amoxicillin: Follow-Up: Macrolides: First-line antibiotics for Alternatives for patients Instruct the patient to the treatment of allergic to penicillin or complete the full course Streptococcus pyogenes when resistance is a of antibiotics. infections. concern. Advise the patient to Effective against group A Cephalosporins (e.g., monitor symptoms and streptococci and have a cephalexin) or seek medical attention if narrow spectrum of macrolides (e.g., there is no improvement activity. azithromycin) may be or if symptoms worsen. considered. Educate the patient about the importance of good respiratory hygiene to prevent the spread of infection. Introduction Various bacterial species often cause upper respiratory tract infections (URTIs), and among them, Streptococcus pyogenes, Haemophilus influenzae Moraxella catarrhalis 1. Streptococcus pyogenes Also known as Group Gram-positive cocci in Beta-hemolytic on A Streptococcus chains blood agar Can lead to more Diagnosed through Commonly causes severe conditions like throat culture or rapid pharyngitis and rheumatic fever, and antigen detection tonsillitis post-streptococcal tests glomerulonephritis  2. Haemophilus influenzae A small, pleomorphic, There are encapsulated Grows best on Gram-negative (serotypes a-f) and non- chocolate agar. coccobacillus. encapsulated strains. Hib (Haemophilus Commonly causes otitis influenzae type b) media, sinusitis, and vaccine has reduced the exacerbations of chronic incidence of severe obstructive pulmonary infections caused by this disease (COPD). bacterium. 3. Moraxella catarrhalis Often causes otitis Gram-negative Grows on blood agar media, sinusitis, and diplococcus. and chocolate agar. lower respiratory tract infections. A common respiratory pathogen in individuals Identification often with chronic involves culture and obstructive pulmonary biochemical tests. disease (COPD). Common modes of transmission: 1. Droplet 2. Contact 3. Environmental Transmission Transmission Factors  When an infected 1. Droplet The transfer of person talks, coughs, or sneezes, respiratory Transmission: respiratory droplets droplets are expelled containing infectious into the air. If a agents from an susceptible person is infected person to a near (usually within susceptible individual. about 6 feet), they can inhale these droplets, leading to infection. 2. Contact Transmission: Bacterial pathogens causing upper Direct contact occurs when there is respiratory tract infections can be physical contact between an spread through contact with infected person and a susceptible respiratory secretions or person. contaminated surfaces. Indirect contact involves the For example, touching a surface transfer of pathogens through with respiratory droplets and then contaminated surfaces or objects. touching the face (mouth, nose, or eyes) can lead to infection. 3. Environmental Factors: Contaminated Objects: Crowded Settings: Poor Ventilation: Contaminated Bacterial pathogens Inadequate surfaces and are more likely to ventilation can objects, such as spread in crowded contribute to the doorknobs, toys, and settings where accumulation of shared equipment, people are in close respiratory droplets can serve as contact, such as in enclosed spaces, fomites, facilitating schools, daycare increasing the risk the transmission of centers, and of transmission. bacteria when healthcare facilities. touched by multiple individuals. Pathogenesis Adherence to Respiratory Mucosa Invasion of Host Cells Evasion of Host Defenses Induction of Inflammation  Pathogenesis Adherence to Respiratory Mucosa Pili and Fimbriae allow bacteria to adhere to respiratory cells Adhesins are surface proteins that promote adherence, such as M protein in Streptococcus pyogenes Invasion of Host Cells Some bacteria can enter host cells through endocytosis Bacterial pathogens may secrete factors that enhance their invasion, such as IgA protease in Haemophilus influenzae Evasion of Host Defenses Bacteria can produce a protective capsule to evade phagocytosis, as seen in Haemophilus influenzae Antigenic variation and enzymatic degradation also aid in evading host defenses in pathogens like Streptococcus pyogenes Induction of Inflammation Bacterial toxins can damage host tissues and trigger inflammation, as seen in Streptococcus pyogenes Bacterial components and cytokines released by pathogens can also contribute to inflammation in Common upper respiratory tract infections 1. Pharyngitis 2. Tonsillitis 3. Sinusitis 4. Otitis Media 1. Pharyngitis (Strep Throat): Sore Throat: A Painful Swallowing: predominant symptom, Swallowing may be painful and often severe and difficult. sudden in onset. Fever: Elevated body temperature, typically Red Tonsils: Inflammation higher in bacterial and redness of the tonsils. infections. Swollen Lymph Nodes: Enlargement of lymph nodes in the neck. 2. Tonsillitis: Severe Sore Throat: Similar to pharyngitis, tonsillitis presents with a severe and painful sore throat. Swollen Tonsils: Tonsils appear enlarged and may have white or yellow patches of pus. Difficulty Swallowing: Painful swallowing is common. Fever: Elevated body temperature is typical. Headache and Fatigue: Generalized symptoms of illness may be present. 3. Sinusitis: Nasal Congestion: Blockage of the nasal passages. Facial Pain or Pressure: Pain or pressure around the eyes, nose, and forehead. Discolored Nasal Discharge: Green or yellow discharge from the nose. Coughing: A cough may be present, especially if postnasal drip occurs. Fever: Systemic symptoms, including fever, may be observed. 4. Otitis Media: Ear Pain: Pain and discomfort in one or both ears. Fever: Elevated body temperature may accompany the infection. Hearing Loss: Temporary hearing loss is possible due to fluid accumulation in the middle ear. Irritability: Especially in children, who may have difficulty expressing ear pain. Drainage from the Ear: In some cases, fluid or pus may drain from the ear.  laboratory techniques 1. Throat Swabs A sterile swab is rubbed against the posterior pharynx and tonsils to collect a sample. often used for the diagnosis of streptococcal pharyngitis (strep throat). 2. Culture Techniques Throat cultures are commonly used to identify Streptococcus pyogenes (Group A Streptococcus), a common cause of bacterial pharyngitis. 3. Rapid Antigen Detection Tests (RADT) RADTs detect specific bacterial antigens in the collected sample. The throat swab is mixed with a reagent, and the resulting mixture is applied to a test strip. Results are obtained within minutes based on the appearance of colored lines. 4. Molecular Diagnostics (PCR) 5. Blood Tests Rapid Antigen Detection Tests (RADT) Prevention 1. Vaccination 2. Hygiene Practices 3. Avoiding Close Contact:  Commonly prescribed antibiotics for bacterial upper respiratory tract infections: Target Streptococcus pyogenes (Group A 1. Penicillins: Example: Amoxicillin Streptococcus) commonly associated with strep throat. 2. Macrolides: Examples: Azithromycin, Used as an alternative for individuals allergic to Clarithromycin penicillin or in cases where resistance is a concern. 3. Cephalosporins: Ex: Cephalexin, Target Broad-spectrum antibiotics effective against Cefuroxime various bacteria causing respiratory infections. Reserved for more severe or complicated cases, as 4. Fluoroquinolones: Ex: Levofloxacin they have a broader spectrum of activity. Target Bacteria: Used in specific situations, 5. Clindamycin: especially when treating anaerobic bacteria. 1. Vaccination: Streptococcus pneumoniae Vaccine Pneumococcal vaccines are available and recommended for certain populations, especially older adults and individuals with underlying health conditions. Haemophilus influenzae type b (Hib) Vaccine The Hib vaccine is part of routine childhood immunization schedules and helps prevent severe infections caused by Haemophilus influenzae type b. Influenza Vaccine Seasonal influenza vaccination can prevent influenza infections, which can contribute to upper respiratory tract complications. 2. Hygiene Practices: Hand Hygiene: Regular handwashing with soap and water, or the use of alcohol-based hand sanitizers, helps reduce the transmission of bacteria from contaminated surfaces to the face. Respiratory Hygiene: Encourage individuals to cover their mouth and nose with a tissue or their elbow when coughing or sneezing to prevent the spread of respiratory droplets. Avoid Touching Face: Discourage touching the face, especially the eyes, nose, and mouth, to minimize the risk of transferring bacteria from hands to mucous membranes. 3. Avoiding Close Contact: Social Distancing: During periods of increased respiratory infections, practicing social distancing can reduce the likelihood of close contact with infected individuals and the spread of bacteria. Thank You